Posts Made By: Philip Canard

I own an LXD75 mount. I was cursing it when it was new, as it had the commonly bent encoder wheels and would not function in GoTo mode. I eventually got it back from Meade and it has worked since, except for the common glitches like keep it out of very cold weather or keep the computerized hand controller warm. I commonly hit most targets at 200X, and that's pretty good GoTo performance for the price. There is an aftermarket for supplying the mount with better bolts, cables and accessories, so you can fix it up with no problem. It handles any scope up to an 8" Newtonian or 6" refractor. It uses Atlas or CG5 counterweights, which are dirt cheap.

What I found was that the polar alignment scope itself needed aligning after it got back from Meade. After that, the optical axis of the OTA must be centered. If the mount is accurate with a Mak or refractor that typically has the optical axis in line with the tube axis, then the mount is doing its job. The SN8 OTA was badly miscollimated on arrival, and when I got the optical axis in line with the polar axis of the mount, then everything was accurate in GoTo mode except the occasionally missed planet which is hard to compute but easy to find visually. The fact that the mount can compensate for huge errors in setup alignment was demonstrated by the fact that when I moved to Montana, I still had the controller set for Arkansas, and targets were in the field of view at 200X, many of them almost dead center. I think the location info mainly determines rise and set times for objects. Objects do not move in relation to Polaris and alignment stars due to a geographical shift, but they may or may not be visible in both places at once.

The reason you may find few of these mounts for sale used relative to new sales, is that when the technical bugs and learning curves are brought under control, there is no reason to move on to something like a GM8 at a much higher price that does hardly anything more but lighten your wallet (except maybe for photography). Most people are not into high end astrophotography, and the mounts work OK for visual work where you are typically limited to 200X mags by seeing conditions. If you need a part, you can usually find it at LXD55.com, and it will be an upgrade over the Meade part. I'm not afraid to work on my LXD75 mount, as it is cheap and not worth sending off anyway when out of warranty. My LXD75 holds a 6" Mak-Cass steady at 350X mag, and that's good enough for me. If I need a steadier mount due to wind, I can use my standard Atlas mount, and since I paid $750 new for it, I am still well under the cost of a standard GM8 that has no GoTo, and I have two mounts I can use simultaneously if I want.

The LXD75 and Celestron CG5 mounts are worth far more than the one-armed Nexstar mounts as they are universal in mounting capability with just about any OTA you acquire up to 8". You often find them for sale where a person bought the outfit with the intention of selling the mount, because you often get the outfit for only a couple hundred bucks more than the bare OTA. Doesn't make sense, but that's how Meade and Celestron market them. In effect, you will save about $200-$300 over buying the OTA outright after you sell the mount, and have some accessories as extras.

I think a GoTo mount is pretty useless for lunar/planetary/double-star service as you just swing over to the target and start observing. I'll just turn on the laser on the Mak and slew to the target without bothering to enter anything in the computer. However, for dim objects in deep sky when I have the Schmidt-Newt mounted, it comes in very handy and you will get a chance to look at many more targets in a night. I suspect that deep sky addicts love their GoTo mounts and are loathe to give them up.

The one armed mounts are limited in scope mounting capability, so very few people would buy an outfit with the intention of selling the mount. The LXD75 and CG5 on the other hand, have huge market appeal and most amateurs have an OTA that could be mounted on them. Unless you intend to use a scope terrestrially, it makes no sense to me to buy a fork or one-armed mount. Could I mount a TEC eyepiece turret on a fork mounted OTA, and would the OTA balance after I did so? Just one of several reasons that demand for a one-armed mount would be relatively low. They stay with the SCT they came with.

I'm half Black Lab, a quarter Rottweiler and a quarter German Shepherd. I like the water a lot, and dislike some British actors, so my name is Jacques (as in Cousteau).

Probably because D&G Optics sells an 8" achromat with Astro Physics focuser for a few thousand dollars that will virtually equal that Tak for visual use. You would have to look close to tell the difference visually, and see if it was worth the 40X price increase.

Brian Cheney explains this pricing phenomenon on his high end loudspeaker website. For some of the most expensive items in high end audio, THE PRICE IS THE PRODUCT. I'm sure that more than a few of those Tak outfits go to oil sheiks and the like that are buying some exclusivity that hardly anybody else can afford. When you are ripping off your country to the order of a few hundred million a year, what is a piddling scope that costs a mere low 6-figure amount? The reason you build a reputation at the high end of the market is so you can set your own price. It's about maximizing profits instead of a cost/benefit ratio to the consumer.

If you want a scope that shows more detail than an 8" TEC, you will have to launch it into orbit to get rid of atmospheric disturbance or put it on a mountain top. Rolando is vcery correct about one thing, the building to house such scopes can exceed the scope cost by several times, so the scope pricing is a minor concern in that case.

Try a bathroom scale. Duh.

To those who have tried collimating a Schmidt-Newtonian or a Maksutov-Newtonian:

I also feel your pain.

I just got through collimating mn Meade SN-8 for the 5th time a few days ago. It is closer to perfect collimation than ever before......BUT

I looked in Weasner's website and he had a few tips to collimate the Schmidt-Newtonian that I never considered. I MIGHT be tempted to try them, if anybody else has seen a better result than by going by the Meade LXD75 owner manual (I know it isn't much, but it's what I started with). I now sort of have my own personal way of doing it since a laser collimator and a peep cap are my main alignment tools.

I used a laser collimator to get my diagonal rotated square with the focuser. If the diagonal is straight in axis with the optical tube and the focuser is square with the optical tube, then the laser dot will hit the mirror in a line parallel to the focuser axis and hopefully in the center of the primary. The dot will move left or right of center if the diagonal mount is rotated counterclockwise or clockwise respectively. You can rotate the diagonal mount from the front without removing the corrector cell. Weasner uses a T shaped template that fits snugly in the focuser tube. I guess that works as well, but I would rather have laser light than a cardboard T template on my mirror, personally.

He also removes the primary to get more light in the tube and places white paper behind the diagonal in order to get the diagonal directly under the focuser. I had a hard time seeing everything when I aligned the diagonal with the focuser tube, and I aimed my OTA at white curtains that were flooded by direct sunlight in order to get enough light into the tube without removing the primary.

One thing he did that I wish that I had done is remove the front cell retaining ring and see if the Schmidt corrector plate was EXACTLY in the center of the cell. If it is off, then the correct mirror offset will not be right when the diagonal is centered under the focuser and/or the secondary will sit to the left or right when the diagonal axis is parallel to the optical tube axis.

I made sure my diagonal was in line with the optical tube axis. The diagonal can thus be square to the focuser and you can pull it forward or backward to get the correct down and back offset. The penalty is a bit of light loss if the diagonal is not exactly centered under the focuser. Light falloff is not nearly as severe at f/4 as it is at f/8 if the mirror is not exactly centered under the focuser and is more of a photographic consideration that a visual consideration.

The method of doing the final alignment by centering the reflections and shadows on the corrector plate by using a Cheshire sight tube and a bright light were new to me. I'll have to get a Cheshire sight tube in order to try that one.

As it is, it sits pretty good as far as a star test goes. I was getting pretty good results even with a less than perfect star test result, but my main use of the scope is deep sky, not planetary or lunar work. The lack of chromatic aberration relative to my Stellarvue Nighthawk achromat refractor seems to have made up for the lack perfect collimation, and my Nighthawk is perfectly collimated, which is standard with just about any Stellarvue scope that hasn't been abused.

Measured at the back of my primary cell, the mirror tilt is within 1/32" from high to low reading measured from the rear of the primary holder to the tube mounting ring. I suspect from that measurement that things must be getting close to excellent collimation. The factory alignment was atrocious with a very definite egg shaped star test.....and the scope still gave up acceptable deep sky views.

I suspect that most Meade Schmidt-Newtonians are poorly collimated. I suspect that those who have halfway decent collimation are rarely seeing anything bad enough to really get into getting theirs perfectly collimated.

As you move the scope around with a heavy binoviewer in the focuser (I use a JMI NGF55), you will see a slight change in the star test due to the bending of the focuser and the weight of the diagonal/corrector plate assembly bending a bit. I collimate my scope with the optical tube pointing straight up and some weight on the focuser. You can then see the laser dot move off center as you move the optical tube all around. I maintain that prefect collimation is thus a bit of a myth, and I try to split the differences and just keep the laser dot in the primary mirror center dot as I move the scope around.

Weasener's method gives him a perfect alignment with the scope tube horizontal........but the funny thing with me is that I rarely use my SN-8 in that orientation.

YMMV

Phil Canard

Floyd, I'm afraid I have you beat in numbers, if not in cost. I had a total of 40 EP's, Barlows, OCA's and a coma corrector at last count. I have 2 more EP's and 2 more OCA's on order. I have 3 binoviewers so far (2 for the SN8 and 1 for the NHII). I haven't even begun to collect 2" EP's yet. Just got the Baader MPCC coma corrector, so an UWA 2" EP is being sought as I type. Mostly the explosion came about as I bought copies of my favorite 1.25" EP's for binoviewing. I have a "big gap" (percentage increase wise) between my 8.9mm Siebert Star Splitter and 12.5mm Ultima pairs, but I do have a single 10mm Ultima I will not be doubling up on. I have 6.4mm SS, 8.9mm SS, 12.5mm Ultima, 15mm Axiom, 18mm Ultima, 20mm Bino-Lite, 21mm Siebert SWA, 23mm Axiom, 25mm Plossl, 30mm Ultima and 32mm Plossl pairs. A pair of 4.4mm Star Splitters will make it an even dozen, I figure. That even dozen figure is nagging at me, then comes "Lucky 13".

Floyd,
I own a 9mm pair of the TMB's. After comparing them to the new 6.4mm Siebert Star Splitter modified Orthos I recently acquired ($89 each for Siebert BV owners), I retired the 9mm TMB's to my spotting scope and one is in my SN8 scope case for monoviewing. The SS EP's are more comfortable in a binoviewer and have less blackouts and kidney beaning issues. Some seem to not have those two problems with TMB's, but the new Siebert design is very resistant to both problems. The Star Splitters heat much easier and faster with my Dew-Not bino heater straps. The slim and lightweight Star Splitters are just the best high power EP's I have ever found for binoviewing, which is no surprise as they come from a binoviewer specialist. They are a new modified Ortho design, and the Ortho is unsurpassed for planetary work. Harry increased the eye relief to 10mm across the whole range, and there are 13 FL's from 2.9mm to 9.9mm. mostly in 0.5mm FL steps so you can buy the exact FL's you need. They are fully as sharp as my Celestron Ultima EP's, just as contrasty and well corrected, but with longer eye relief and more comfort in short FL's. I have the 8.9mm Star Splitter on order in a matched bino pair. At that FL, they are only $69 each for a Siebert BV owner and thus $30 less than the TMB's and made in the USA to boot with a money back satisfaction guarantee. I figured there's nothing to lose, and if they are as good as the 6.4mm Star Splitters, they are really high value. It's good to know you don't have to buy EP's from China these days to get a good price and excellent performance.

I have the Siebert 1.8X MaxLight OCA with the 1.25X and 2.8X OCA's on order and due to arrive any day now, along with my new 8.9mm Star Splitter modified Orthos with 65 degree AFOV. While the OCA is good, I was really blown away with the Star Splitters. They are very comfortable for me, almost as if I designed them for myself. YMMV, but Harry does give a money back guarantee.

Joe,

I would advise studying the charts over at the JMI website. My JMI NGF-55D 2-speed has 1.2" of travel and a standard length of 3". This is about minimum length to give a range of focus and not intrude into the light path. JMI has several drawtube length options for $12 extra at time of order. I would advise ordering direct from JMI as your credit card will not be charged until the unit ships. I paid for mine up front through Astronomics and then waited a month until the next production run at JMI. There are so many options for JMI focusers that it's best to call unless you want to study charts until your hair hurts.

Also, you might consider a Baader 2" T2 nosepeice and a Baader Click-Lock EP Clamp. It gives you about 32mm of extra out focus and instant and secure EP changeouts. I'll never go back to thumbscrews! Astro-Physics has free shipping on Baader products and sometimes a bit lower price than other Baader dealers, which are few in the USA. I go to the low profile 1.25" JMI EP clamp if the Click-Lock isn't short enough. Many JMI focusers now come with T2 threads on the 1.25" reducer, so you don't need the $41 Baader T2 nosepeice to mount the Click-Lock EP clamp. The Click-Lock deserves a LOT more attention than it has gotten since its introduction, as the anachronistic thumbscrew EP clamps are finally getting phased out. Axial alignment is automatic with a Baader Click-Lock ($66 at A-P), it puts a death grip on the EP with little turning force, and I will figure one into the focuser sizing for my setup from here on out. It seems built to last a lifetime with very smooth operation. Jacking the EP up a bit to increase outfocus will not affect automatic axial alignment.

If I hadn't bought the Click-Lock, I would have needed the 1.5" extension tube to bring my EP's to focus. As it now stands, I can adjust in or out about 1.5" so I have nearly 4" of total travel with my setup. A 40mm Baader T2 extension tube is $25 from A-P, which kicked me out to around 5.5" of total travel available with a 1.2" travel focuser as I can set it up 4 different ways to achieve focus.